Fluid pressure brake



Nov. 16, 1937. R. J. BUSH FLUIDPRESSURE- BRAKE Filed May 29, 1955- Paienied Nov. 1c, 1937 Y l y Zegggi Fries d FLUID* PRESSURE BRAKE Rankin J. Bush, Jeannette, Pa., assigner to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application May 29, 1935, Serial No. 24,037

12 Claims. (Cl. 303-19) This invention relates to fluid pressure brakes functioning of the self-lapping brake valve deand particularly to control'apparatus for convice. Y

trolling fluid pressure brakes adapted for use Another object of the invention is to provide on railway vehicles. a brake system incorporating safety control ap- 5 One type of fluid pressure brake equipment paratus which is responsive to variations in the 5;: now in use includes a self-lapping brake Valve pressure of the fluid in the safety control pipe, device for controlling the supply of. uid under and which is rendered inoperative in the event pressure to and the release of fluid under presthat a predetetermined application ofthe brakes sure from the brake cylinder to effect the aphas previously been effected.

le plication and release of the brakes and safety A further object of the invention is to prol;

control apparatus for effecting an emergency vide a brake system incorporating safety control application of the brakes when the operators apparatus which is responsive 'to Variations in foot is removed from a pedal so that in the event the pressure of the fluid in a safety control pipe, of incapacitation of the operator, such as sudand which is operative, on an application of the l den illness or death, the consequent release of brakes produced by a release of fluid from the l5;

pressure on the foot pedal will cause what is safety control pipe, to prevent the release of the commonly known as dead mans emergency apbrakes until the pressure of the uid in the plication of the brakes. safety control pipe is reestablished.

In certain systems now in use, on an emergency Other objects of, the invention and features of brake cylinder through the self-lapping brake scription taken in connection with the accomvalve devices employed in these systems, and panying drawing, the single figure of which is the rate of now of fluid to the brake cylinder a diagrammatic view of a brake system emhas been limited by the capacity of the ports in bodying my invention.

no application of the brakes, fluid is supplied to the novelty will be apparent from the following de- 20,

gf, the self-lapping brake valve devices, with the Referring to the drawing the embodiment of result that the rate of brake application on an the invention therein illustrated comprises a emergency application of `the brakes is not as brake cylinder l, a reservoir 2, the supply of fluid i rapid as is desired. from said reservoir to and the release of fluid It is the principal object of this invention to from the brake cylinder l being controlled by 3o provide a brake system incorporating safety a brake valve device 3, which may be of the self- 30v control apparatus which, when effecting an lapping type, and by a fluid pressure responsive emergency application of the brakes, operates to valve device 4i, the operation of the brake valve supply fluid under pressure to the brake cyldevice 3 and the fluid pressure responsive valve inder at a faster rate than that permitted by device 4 being controlled by a manual brake conthe self-lapping brake valve device. trol device 5. The system also includes an auto- 35,

A further object of the invention is to promatic rail sanding device indicated at 6. vide a brake system incorporating safety con- The brake valve device which is of. the selftro-l apparatus which, in effecting an emergency lapping type, comprises a main casing section application of the brakes, operates to supply I0 and a valve section H, which when assembled fluid under pressure to the brake cylinder through together dene a pressure chamber l2. 40

a passage independent of the self-lapping brake The valve section il `is provided with a valve valve device, whereby on an emergency applicachamber I3, which is in constant communication tion of the brakes the rate of ow of fluid to the with the reservoir 2 by way of a pipe lll, and brake cylinder is independent of the capacity of which contains a supply valve element It, which Ll5 the ports through the self-lapping brake valve is urged to its seat by a coil spring l'l, and 4,5v

device. which controls communication between the valve A further object of. the invention is to provide chamber i3 and the pressure chamber l2. a brake system incorporating safety control apvThe valve section ll also is provided with a paratus, which in effecting an emergency applipiston chamber 23, in which is mounted a piston cation of the brakes operates to supply fluid 2l,`whichisprovided with a valve chamber 22, 50,'

lunder pressure to the brake cylinder through a which vis in communication with the pressure passage independent of the self-lapping brake chamber l2 by way of a passage 23. Thevalve valve device, whereby on an emergency applichamber 22 has positioned therein a release valve cation of the brakes the supply of fluid to the element 25, which is biased to the un-seated po- 5.5` brake cylinder is not dependent on the proper sition by the coil spring 26, and when the valve 55,

element 25 is in its un-seated po-sition the valve chamber 22 is in communication with the atmosphere by way of the passage 28, the piston chamber 20, and the passage 29, and when the release valve is in its seated position this communication is cut off.

The piston 2| is subject on one side to the pressure of the uid in the pressure chamber l2, and on the other side to the pressure of the coil spring 3| which extends between the piston 2| and an abutment 33.

The abutment 33 is pro-vided with a central bore 35 adapted to receive a reduced extension 31 of the piston 2|, while a regulating screw 39 is adapted to extend into the bore 35 to limit the amount of movement of the piston 2| to the left as viewed in the drawing.

For actuating the supply valve element I6 to its unseated position, and the release valve 25 tothe seated position, there is provided a mechanism including a lever 4|, which is secured intermediate its ends by the pin 42 to a floating pivot carrier 43, which is slidably mounted in a bore 44, in the valve section and in a guiding lug 41 formed integral with the main casing section I0.

A stem is pivotally secured to the lower end Vof the lever 4| and extends into a bo-re in the end of the supply valve element |6,`while a roller 52 is pivotally mounted on the other end of the lever 4| and is adapted to engage the rounded end of the release valve element 25.

The springs I1, 26, and 3| are of different values, the spring I1 being of greater resistance than the spring 26, and being of less resistance than the springV 3|.

When the floating pivot carrier 43is moved to the left as viewed in the drawing, the lever 4| will pivot on the pin 42, and the release valve element 25 will be moved to the left against the pressure of the spring 26 so as to close the passages controlled thereby. On engagement of the release valve element 25 with its seat, and on further movement of the floating pivot carrier 43 to the left, the lever 4| will pivot on the axis formed by the roller 52, and the supply valve element |6 will be moved toV the .left to open the passage leading from the reservoir 2 to the pressure chamber I2. The spring 3| is of such value, and the lever 4| and the associated members are so proportioned, that movement of the floating carrier 43 does not affect the position of the piston 2|.

For actuating the oating pivot carrier 43 there is provided a lever which is mounted on a shaft 56, which is journaled in the main casing section I0, and which projects through the casing section wall and has a lever 58 secured thereon outwardly of the chamber |2. A springV 58 extends between the lever 58 and a projection on the casing section l0 and normally urges the lever 56 to rotate in a clockwise direction. v

The lever 55 engages the end of the floating pivot carrier 43, and engages a stop B2 secured to the main casing section I0, and which limits movement of the shaft 56 and lever 55 in a clockwise direction.

The fluid pressure responsive valve device 4 is constructed of a plurality of casing sections which have formed therein a piston chamber 10 which is in constant communication with the safety control pipe 1|, and which has positioned therein a piston 12, which is mounted on a stem 13,' slidably mounted in a bore in one of the casing sections,l and which has secured o-n the other end thereof a valve 15 adapted to engage a seat .absage-i rib 16. The piston 12 is subject on one side to the pressure of the fluid in the chamber 10 and is subject on the other side to the pressure of the spring 14. l

The valve 15 has an arm 18 associated therewith which carries a valve 18 which is held away from the Varrn 18 by means of a spring 80 and which controls communication between a chamber 8| and the atmosphere by way of a chamber 82, open to the atmosphere, in which the valve 19 is positioned. The arm 18 is engageable with the stem of a valve 85 which is mounted in a chamber 86, and which is urged into engagement with a seat rib- 81 by a spring 88. The chamber 86 is in constant communication with the reservoir 2l by way of the pipe and passage 90.

The casing of the fluid pressure responsive valve device 4 also has formed therein a bore in which is mounted a piston 96 which has formed integral therewith a stem 91, and which is engageable with a seat rib 98, the area inwardly of the seat rib 98 being in constant communication with the chamber 8|, while the chamber 95 on the left hand side of the piston 96 and outwardly of the seat rib 98 is in constant communication with a passage 99.

The chamber 95A- on the right hand side of the piston 96 is in constant communication with the atmosphere by way of the passage |00.

The stem 91'has secured on the other end thereof a piston |02, which is of somewhat smaller diameter than the piston 96, but of larger diameter than the seat rib 98. This piston is mounted in a bore forming a chamber |03 at the right hand side of the piston, which is in constant communication with the pressure chamber 2 in theV self-lapping brake valve device 3 by way of the passage |04 and the pipe |06.

The chamber |83A at the left hand side of the piston |02 is irl-constant communication with the atmosphere by Way of the passage |00.

The passage 99 is in constant communication with an automatic rail sanding device, indicated diagrammatically at 6 on the drawing, communication being by way of the passage H0, having a choke or restricted portion interposed therein, and a pipe |I2.

The fluid pressure responsive valve device 4 is provided with a chamber ||5 which is in constant communication with the brake cylinder by way of a pipe ||1.

A double check valve ||8 is mounted in a bore of the'casing which opens at its opposite ends into the chamber ||5 and said check valve is adapted to engage a seat rib |20 surrounding the passage |04, to control communication between passage |04 and the chamber II'5, and a seat rib |24 surrounding the passage 99, to control communication between the passage 99 and the chamber ||5.

The` casing of the fluid pressure responsive valve device 4 has formed integralV therewith a bracket |25 in which is jcurnaled theV end of the rod 5E. The rod 56 has secured thereon a locking disk |21, while the casing of the iiuid pressure valve device 4 has formed thereon adjacent the locking disk |21 a cam surface |28.

A lever |30 is pivotally secured on the casing of the fluid pressure responsive valve means 4 by means of a pin |3|, and has an angular'end portion |32 projecting through an opening in the piston chamber 10 so as to be engaged by the piston 12. The other end of the lever |38 has pivotally secured thereto, through a pin |34, an arm |35, which carries aroller |36 which is positioned between the locking disk |21 and the cam direction against the spring |40.

surface |28. The lever |30 is biased to move in a counterclockwise direction by means of the springV |40 and is urged in the opposite direction by the piston 12.

When the piston 12 is moved to the left as viewed in the drawing the spring |40 causes the lever |30 to rotate` in a counterclockwise direction, and the arm |35 causes the roller |36 to move into engagement with the locking disk |21 and the cam surface |28, and thereby prevent rotation of the locking disk |21 and the shaft 56 in a clockwise direction, that is, in a direction to effect a release of the iluid in the brake cylinder through the self-lapping brake valve 3.

The manual brake control device 5 comprises a base member |40, a cover |4|, and a pair of valve sections |42 andV |43.- The control device is adapted to be mounted upon thev oor of the vehicle, and has a chamber |44 therein, in which is mounted a forked lever |45 having a hub portion |46, anda pair of spaced arms |41. This lever is pivotally mounted on a shaft |48 supported by the casing cover section |4|. The arms |41 each 'have a recess |49 therein into which extends a spring |5| and which normally urges the left hand end of the arm upwardly as viewed in the drawing.

The lever |45 has a valve operating finger |54 formed integral therewith and adapted to engage the end of the stem of a valve |58.

A foot pedal |60 is provided and is formed lntegral with an arm |6| which is pivotally mounted on a -pin |63 which extends between the arms |41, and which has pivotally secured on the end thereof, by means of a pin |55, a link |61, the other end of which is pivotally secured by means of the pin |60-to one arm of the bell crank |10 which is mounted on the casing section |4| by means of a pin |12. The other arm ofthe bell crank has connected thereto by means of a pin |14 a rod |30 which has its other end connected to the lever 58 by means of apin |8I.

The casing sections |42 and |43 cooperate to `form a valve chamber y|90 which is in constant communication with the safety control pipe 1|, and which has mounted therein the valve |58,

and a valve |9|, which are separated by a washer in the drawing by pressure applied by the operators foot, and that the heel portion of the foot pedal is depressed, as shown, the operating finger |54 is maintained out of engagement with the end cf the valve |58, so that this valve is permitted to seat. vAt the same time fluid under pressure in the pipe |96 forces the valve |9| to the unseated positiomso that fluid under pressure flows from the reservoir 2 by way of the pipes 90 and |96 to the valve chamber |90, and therefrom to the safety control pipe 1| which leads to the chamber 10 in the fiuid pressure responsive valve means 4. The fluid under pressure in the chamber 10, acting on the piston 12, moves this piston to the vextreme right hand position, and moves the lever |30 in a clockwise This causes the roller |36 to be moved outv of engagement with the cam surface |20, and thereby releases the locking disk |21 and the shaft 56. This permits the spring to move the lever 58 and thereby rotate the shaft in a clockwise direc tion so that the arm 55 is moved against the stop 02 and so that the oating pivot carrier'43 is permitted to move to the extreme right hand p0-V sition thereby permitting the supply valve I6 to.

seat and permitting the release valve 25 to be unseated. Y

When the release valve 25 isv unseated, the chamber |2, and the brake cylinder which is in communication with the chamber I2 by way of the pipe |1, the chamber H5, passage |04 and pipe |06, are open to the atmosphere.

If it is desired to effect a service application of the brakes the foot pedal |08 is rotated by moving the toe portion of the foot pedal downwardly, thus causing the lever l'ly to be turned in a clockwise direction. about the pin |53 on which it is mounted and moving the link |61 vdownwardly. Movement of the link |01 is 'transmitted to the bell crank |10 so as to move the bell crank in a counterclockwise direction, and movement of the bell crank is transmitted through the rod |80 to the lever 58, thus causing the shaft 55 to be rotated in a counterclockwise direction.`

When the shaft 50 is rotated in a ccunterclockwise direction the arm'55, which engages the end of the floating pivot carrier 43, moves the oating pivot carrier to the left, as viewed in the drawing, and on movement of this member the release valve 25 is first moved into engagement with its seat, so as to cut oif communication from the chamber l2 tothe atmosphere, and, on further movement of the floating pivot carrier 43, the pin 50 presses against the supply valve l causing it to move away from its seat, withthe result that iuid under pressure flows from the reservoir 2 by way of the pipe |4 and the valve chamber I3 to the pressure chamber |2 and there# from to the brakecylinder. Fluid flows from the pressure chamber i2 to the brake cylinder by Way of the pipe |055, which communicates withY the passage |04, and the flow of fluid tothis passage causes the double check valve H8 to move into engagement with the seat rib |2|, if l it is not already in engagement with this seat rib. Fluid can then flow from the passage 01| pipe to the brake cylinder I.

When the pressure of the fluid in the brake. cylinder and in the pressure chamber |2 builds up to a sufficient value, this value depending upon the position to which the loating pivot carrier 43 has been moved, the piston 2|, which is subject on one side to the pressure in the pressurechamber |2, will be moved against the spring 3|, and, on movement of the piston 2| to the left, the spring l1 acting through the supply valve I6 and the pin 5|!" will cause the lever 4| to pivot about the pin 42 until the supply valve I6 is moved into engagement with its seat, there by*v cutting oif the flow of fluid from the reservoir 2 to the pressure chamber |2 and to the brake cylinder. The further supply of fluid to the brake cylinder is then cut off.

If it is desired to increase the degree of application of the brakes the toe portion of the foot pedal is moved downwardly a greater dis-1 tance, and this causes the floating pivot carrier 43 to be moved to the left a greater distance, with the result that the pressure inl the-pressure chamber |2 must build up to a greater value to the chamber H5 and therefrom by way ofthe l before the piston 2| compresses the spring 3|Y an amount sufficient to permit the supply valve I6 to be moved to its seat.

If it is desired to decrease the degree of application of the brakes the toe portion of the foot pedal |60 is partially raised, and this permits the shaft 56 and the arm 55 to move in a clockwise direction being urged in this direction by the spring 59 acting through the arm 58, and, on movement of the arm 55m this direction, the oating pivot carrier 43 will be released from the release Valve 25 so as to permit this valve to be unseated by the spring 25, thereby permitting the release of fluid from the pressure chamber I2 to the atmosphere. Fluid will be released from the chamber l2 and from the brake cylinder until the pressure in the chamber I2 is reduced so that the spring Si will move the piston 2| to the right until the seat on the piston is in engagement with the release valve 25; This will cut off the further release of fluid under pressure from the pressure chamber l2 and from the brake cylinder and the iluld pressure remaining Yin the brake cylinder will be held.

If, at a time when the brakes are released, the operator removes his foot from the pedal Hill, either intentionally or otherwise, the arms lli'i or" the forked lever |45 in the manual brake control device 5, will be urged upwardly by the springs |5|, and the valve operating nger li will engage the stem on'the valve |53 and cause this valve to be moved away from its seat, and at the same time this valve will press against the valve I'SI and move this valve to its seated position so as to cut 01T the flow of fluid from the reservoir to the valve chamber IQ@ by Way of the pipes Se and |96. When the valve |58 is unseated the fluid in the valve chamber 96, and in the safety control pipe 1|, is permitted to escape to the atmosphere, thus reducing the pressure of the fluid in the chamber lil in the fluid pressure responsive valve device d.

When the pressure of the fluid in the chamber 1U is reduced the piston l2 is moved to the left, as viewed in the drawing, by the spring ld, and on movement of the piston the stem i3 and the Valve 'l5 are also moved until the valve 'i5 seats on the seat rib 16 so as to cut off communication 50; between the chamber 8| and thel atmosphere around the stem 73. When the valve 'l5 is moved to the left as viewed in the drawing, the valve IQ-will be moved to its seat, and will be held in the'seated position by force transmitted from the arm 'l through the spring 86, and on further movement of the valve 'l5 the end'of the arm i8 will engage the end of the stem on the valve Se and move this valve away from the seat rib 8l against the pressure of the spring 83. When the valve is unseated fluid un-der pressure is per'- mitted to flow from the reservoir E by way of the pipe and passage S6 to the chamber d, and therefrom to the chamber 8i.

The" pressure of the fluid in the chamber 8| operating on the area of theA piston 9S within the seat rib 98 is great enough, when the pressure of theluid in the chamber |83 is at atmospheric pressure, or is below a low predetermined pressure to move the piston Q to the right, as viewed in the drawing, away from the seat rib Q8 and thereby permit fluid to iiow from the chamber 8| to the chamber 95 on the left hand side of the piston 96, from which it ilows to the passage 99.

When uid under pressure is supplied to the passage" 979; the double check valve H8 is forced away from the seat rib |2| and into engagement with the seat rib |29. This permits fluid to flow from the passage 99 to the chamber H5, and, therefrom by way of the pipe to the brake cylinder i. At this time the flow of fluid from the chamber H5 to the passage m4, and therefronrby way ofthe pipe |06 to the pressure chamber l2 in the self-lapping brake valve device S, from which it could escape to the atmosphere through the open release valve 25, is cut off by the double check Valve ||3 which is in engagement with the seat rib |20.

Fluid under pressure also flows from the passage 99 to the automatic rail sanding device 6 by way of the choke Hi and the passage H0 which communicates with the automatic sanding device 5 by way of the pipe H2. On an emergency application of the brakes, therefore, the automatic sanding device operates automatically to supply sand to the rails in order to assist in stopping the Vehicle.

YIt will be seen that when fluid is supplied to the brake cylinder as a result of the reduction in the pressure of the fluid in the safety control pipe it is supplied through a passage which is independent of the self-lapping brake valve 3, with the result that the rate of flow is notlimited by the capacity of the passages in the self-lapping brake valve.

In addition, it will be seen that as fluid is supplied to the brake cylinder independently of the self-lapping brake valve on the release of fluid from the safety control pipe, the supply of fluid to the brake cylinder is not dependent in any way on the proper operation of the self-lapping brake valve. it is possible, therefore, to secure an application of the brakes by releasing the fluid in the safety control pipe even though the selflapping valve device should be rendered inoperative. f

In order to release the brakes after an emergency application eected by the release of fluid from the safety control pipe the operator again applies pressure to the heel portion of the pedal E so as to force the arms Ml downwardly against the springs ll and thereby move the valve operating nger lbf! out of engagement with the endl of the valve |58. The valve |53 is then moved to its seat by the spring ISG so as to cut off communication between the safety control pipe 'll and the atmosphere, and at the same time the valve 9i is moved to the unseated position by the pressure of lthe fluid in the pipe |96, and fluid thereupon ows from the reservoir 2 by way of the pipes 9S and |95 to the valve chamber |90, and therefrom to the safety control pipe 'll and to the chamber lil.V

When the pressure of the uid in the chamber l@ builds up to a sufficient value the piston 'I2 will be forced to the right, as viewed in the drawing, against the spring i@ and against the pressure of the fluid in the chamber 8| acting on the valve element l5, and Von movement of the piston l2, the stem i3 and the valve l5 will also be moved, with the result that the arm 'i8 will be moved out of engagement with the stern on the valve 85 thereby permitting this valve to seat, while the Valve I9 will bey unseated with the result that fluid under pressure will be permitted to escape from the chamber Si to theV atmosphere by way of the passage Ei. The supply of fluid under pressure to the chamber li from the pipe Sil which communi- Cates with the reservoir 2 will be cut off when the valve 85 is moved to its seat by the spring 88.

When fluid is'released from the chamber 8| it is also released from the brake cylinder I through the pipe H1, the chamber ||5, past the double check valve I8 `to the passage 99, and therefrom to the chamber 95 on the left hand side of the piston 96, and past the seat rib 98 to the chamber 8|, thereby effecting a release of the brakes.

On a service application of the brakes following the release of the brakes after an emergency application, fluid under pressure is supplied from the pressure chamber I2 by way of the pipe |06 to the passage |64, and the pressure of the fluid in this passage forces the double check valve I I8 out of engagement with the seat rib |20 and into engagement with the seat rib I2 I, thus cutting olf communication between the chamber I I and the passage 99 which is in communication with the atmosphere. At theV same time fluid under pressure iiows from the passage |04 to the chamber |03, and the pressure of the fluid in this chamber operating on the piston |02 moves this piston to the left, as viewed in the drawing, and movement of this piston is transmitted through vthe stem 91 to the piston 96 and forces this piston into engagement with the seat rib 98.

The braking system provided by this invention also provides means by whichthe operator after effecting a service application of the brakes to a predetermined degree may remove his foot from the foot pedal of the manual brake control device without producing an emergency application of l the brakes. The equipment then operates to prevent a release of the brakes until the operator `returns his foot tothe foot pedal of the manual vbrake control device and operates this device to restore the pressure of the fluid in the safety control pipe, but at all times permits the degree of application of the brakes to be increased.

This permits the operator to apply the brakes with sufficient force to hold the car on a track, and then leave the car without causing an emergency application of the brakes.

In order to accomplish this result the operator rst effects a service application of the brakes by pressing on the toe portion of the foot pedal |60, thereby causing the arm lIGI to pivot on the pin |63 and moving the bell crank |10 in a counterclockwise direction which produces similar movement of the shaft 56. This shaft moves theiloating pivot carrier 43 to a position to cause the release valve 25 to move to the seated position, while causing the supply valve I6 to move to the unseated position and permit fluid to flow from the reservoir 2 to the pressure chamber I2 and therefrom to the brake cylinder. n f

The fluid inthe pressure chamber I2 iiows from this chamber through the pipe |06 to the passage |94 and presses the double check valve I I 8 against the seat rib |2| to cut off the flow of fluid from the chamber H5 to the passage 99. Fluid also ilows from the passage |04 to the chamber |03 where the uid which operates on the piston |02 forces the piston to the left, as viewed in the drawing, and the force exerted on this piston is Vtransnriitted through the stem 91 to the piston 96 and presses this piston against the seat rib 98.

'As will be seen in the drawing the piston |02 is substantially larger in diameter than the area within the seat rib 98. f f

When theV pressure of the fluid in the brake cylinder has built up to a Value sufficient to produce a predetermined application of the brakes sufcient to maintain the vehicle against movement the operator lifts his heel from the pedal |60 of the manual brake control device 5 while maintaining pressure on the toe portion of the pedal, thus permitting the foot pedal |60 and the arm |6| to pivot about the pin |65, while maintaining the bell crank and the shaft 56 in substantially the position to which they have been moved. When the pedal lpivots about the pin |65 the arms |41 are raised upwardly by the springs |5I, and the valve operating finger |54 engages the end of the valve |58 so as to unseat this valve and to move the valve |9| to its seat. This causes the supply of fluid under pressure to the safety control pipe to be cut olf, and releases the fluid in the safety control pipe to be Vented to the atmosphere.

When uid in the safety control pipe 1| is vented to the atmosphere, fluid from the chamber 10 is also vented and the piston 12 is moved to the left, as viewed in the drawing, by the spring 14. When the piston 12 moves the stem 13 moves also and the valve 15 is moved into engagement with the seat rib 16, while the arm 18 moves the valve 19 into engagement with its seat, and also engages the stem on the valve 85 so as to move this valve away from the seat rib 81.

When the valve 85 is unseated fluid under pressure flows from the reservoir 2 by Way of the pipe 90 to the chamber 86 and therefrom to the chamber 8|. The pressurev of the fluid in this chamber operates on'the portion of the piston 96 within the seat rib 98, but because of the relatively small area of this portion as compared to the `relatively large area of the piston |62 the force exerted by the fluid operating on the piston 96 is insuicient to move this piston out of engagement with the. seat rib 98. Movement of the piston 96 the piston |02 is of substantially larger diameter than the area within the seat rib 98, the vforce exerted on the piston |02 exceeds that exerted on the piston 96 by the fluid within the seat rib 98, providing the pressure of the fluid in the chamber |03 exceeds a predetermined value. therefore, will not be supplied to the brake cylinder as a result of venting fluid from the safety control pipe.

When the piston 12 moves to the left out of engagement with the end |32 of the lever |30 the spring causes this lever to rotate in a counterclockwise direction on the pin I3I, and as a. result the roller |38 is moved into engagement with the locking disk |21 and the cam surface |28, so

Fluid,

as to lock the locking disk |21 against rotation in a clockwise direction by the spring 59 or otherwise, that is, in a direction to move the selflapping brake valve to the release position. The roller |36, however, does not interfere with rotation of the locking disk |21, and therefore ofthe shaft 56 which controls the self-lapping brake valve, in a counterclockwise direction, that is,

in a direction to increase the degree of application of the brakes.

In order to eifect a release of the brakes it is necessary to restore the pressure of the fluid in the chamber 10 and thereby cause the piston 12 to be moved against the spring 14, and to engage the end |32 of the lever |30 to move the roller |36 out of engagement with the locking disk |21 and the cam surface |28. This will again permit the shaft 56 to be rotated in a clockwise direction so as to condition the self-lapping brake valve device to release uid from the brake cylinder. The pressure of the fluid in the safety control pipe 1| and the chamber 10 will be restored when the operator again presses downwardly on the heel portion of the pedal l5@ of the manual brake control device so as to cause the arms |41 to move downwardly and thus move the valve operating nger ifl out of engagement with the valve |58. l

While one form of the brake control apparatus provided by this invention has been illustrated and described in detail, it should be understood that the invention is not limited to these details of construction, and that numerous changes and modifications may be made without departing from the scope'of the following claims.

YHaving now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a fluid pressure brake,in combination, a brake valve device operable to supply fluid under pressure to a brake cylinder to effect an application of the brakes, manually operated means for operating said brake valve device, iluid pressure responsive means for supplying fluid under pressure to the brake cylinder, and means subject to and operated by the fluid under pressure supplied to the brake cylinder by the brake valve device on a partial application of the brakes for cutting olf the communication through which the last named means supplies fluid to the brake cylinder.

2. In a fluid pressure brake, in combination, a. brake valve device operable to supply fluidunder pressureto a brake cylinder to effect an application of the brakes, manually operated means for operating said brake valve device, fluid pressure responsive means for supplying fluid under pressure to the brake cylinder independently of the brake valve device, and means subject to vand operated by the uid under pressure supplied to the brake cylinder by the brake valve device on partial application of the brakes for cutting off the communication through wln'ch Ythe last named means supplies fluid to the brake cylinder.

3. In a fluid pressure brake, in combination, a brake cylinder, a brake valve device operative to supply fluid under pressure tothe brake cylinder at a limited rate for effecting service applications of the brakes, a safety control pipe, means operative on the release of manually applied pressure to cut oif the supply of fluid under pressure to the safety control pipe and to release fluid therefrom, and valve ,means operative upon `a reduction in fluid pressure in said pipe for supplying ,fluid under pressure to the brake cylinder at a faster rate than said brake valve V devic-e.

4. In a fluid pressure brake, in combination, a brake valve device operable to supply fluid under pressure to a brake cylinder V to effect an application of the brakes, a safety control pipe, means responsive to the pressure of Afluid in the safety control pipe and controlling the supply of fluid to the brake cylinder, manually operated means comprising an oscillatable member movable between a release position and an application position for operating the brake valve device, means yieldingly urging said member to the release position, a cam surface adjacent the oscillatable member, a locking member positioned betweenV a safety control pipe normally charged with fluid under pressure, a manually operated valve device for supplying fluid under pressure to and for releasing fluid under pressure from said brake cylinder, valve means operative on a reduction in the pressure of the fluid in the safety control pipe to supply fluid under pressure to the brake cylinder through a passage independent of the said valve device, means subject to the pressure of the fluidsupplied to the brake cylinder by the said valve device and operative on an increase in said pressure to a predetermined value present on a partial application of the brakes to cut off the communication through which fluid under pressure is supplied to the brake cylinder by operation of the said valve means.

6. In a fluid pressure brake, a brake cylinder, a safety control pipe normally charged with fluid underv pressure, a brake valve device operative to supply fluid under pressure to the brake cylint der at a rate limited to that desired'in effecting serviceV applications of the brakes, valve means operative on a reduction in the pressure of the fluid in the safety control pipe to supply fluid under pressure to the brake cylinder independently of the brake valve device at a fasterl rate than said brake valve device, and means subject to the pressure of the fluid supplied to the brake cylinder bythe said valve device and operative on an increase in said pressure to a predetermined value present on a partial application of the brakes` to cut off the communication through which fluid under pressure is supplied to the brake cylinder by operation of the said Valve means. Y

'7. In a fluid pressure brake, in combination, a brake cylinder, a brake valve device operative to supply fluid under pressure to and release fluid under pressure from the brake cylinder, a member movable between a release position and an application position for controlling said brake Valve device, means yieldingly urging said member to `the releaseY position, a safety control pipe, Valve means operative upon a reduction in safety control pipe Apressure for also supplying fluid under pressure to the brake cylinder, and means subject to and operated on a reduction in safety control ypipe pressure to prevent release movement of the said movable member.'V

8. lIn a fluid pressure brake, in combination, a brake cylinder, a brake valve device operative to supply fluid under pressure to and release fluid vunder pressure fromthe brake cylinder, a member movable Vbetween a release position and an application position for controlling said brake valve device, means yieldingly urging said member to the release position, a safety control pipe, valve means operative on a reduction in safety control pipe pressure to supply fluid under pressure to the brake cylinder independently Aof the brake Valve device, and means subject to and operated on a reduction in safety control pipe pressure to prevent release movement of the said movable member.

Y 9. In a fluid pressure brake, in combination, a brake cylinder, a Vbrake Valve device operative to supply fluid under pressure to and release fluid under pressure from the brake cylinder, a member movable between a release position and an application position for controlling said brake valve device, means yieldingly urging said member to the release position, a safety control pipe, Valve means operative on a reduction in safety control pipe pressure to supply fluid under pres- Sure to the brake cylinder independently ofthe brake valve device, means subject to the pressure of the fluid supplied to the brake cylinder by said brake valve device and operative on an increase in said pressure to a predetermined value present on a partial application of the brakes to cut olf the communication through which fluid under pressure is supplied to the brake cylinder by operation of the said valve means, and means subject to and operated on a reduction in safety control pipe pressure to prevent release movement of the said movable member.

l0. In a uid pressure brake equipment, in combination, a brake cylinder, a self-lapping brake valve, a member movable from a release position through an application Zone to condition the brake valve to supply'fluid under pressure to a passage through which fluid may be supplied to the brake cylinder, the brake valve being adapted to supply fluid to the brake cylinder at pressures which vary in accordance with the extent of movement of the movable member away from the release position, means yieldingly urging said movable member to the release position, a safety control pipe, means operative on the release of manually applied pressure for cutting off the supply of fluid under pressure to said safety control pipe and for releasing fluid therefrom, and means subject to and operated on a reduction in the pressure of the fluid in the safety control pipe for preventing movement of said movable member towards the release position.

11. In a fluid pressure brake equipment, in combination, a brake cylinder, a `self-lapping brake valve, a member movable from a release position through an application Zone to condition the brake valve to supply fluid under pressure to a passage through which uid may be supplied to the brake cylinder, the brake valve being adapted to supply fluid to the brake cylinder at pressures which vary in accordance with the extent of movement of the movable member away from the release position, means yieldingly urging said movable member to the release position, a safety control pipe, means operative on the release of manually applied pressure for cutting off the supply of fluid under pressure to said safety control pipe and for releasing fluid therefrom, means subject to and operated on a reduction in the pressure of the fluid in the safety control pipe for preventing movement of said movable member towards the release position, and valve means subject to and operated on a reduction in the pressure of the fluid in the safety control pipe for also supplying fluid to the brake cylinder.

l2. In a fluid pressure brake equipment, in combination, a brake cylinder, a self-lapping brake valve, a member movable from a release position through an application Zone to condition the brake valve to supply fluid under pressure to a passage through which fluid may be supplied to the brake cylinder, the brake valve being adapted to Supply fluid tothe brake cylinder at pressures which vary in accordance with the extent of movement of the movable member away from the release position, means yieldingly urging said movable member to the release position, a safety control pipe, means operative on the release of manually applied pressure for cutting off the supply of fluid under pressure to said safety control pipe and for releasing fluid therefrom, means subject to and operated on a reduction in the pressure of the fluid in the safety control pipe for preventing movement of said movable member towards the release position, valve means subject to and loperated on a Vreduction in the pressure of the fluid in the safety control pipe for also supplying fluid to the brake cylinder, and. means; subject to the pressure of the fluid supplied by the brake valve and operative on an increase in said pressure to a predetermined value present on a partial application of the brakes to prevent the supply of fluid i 

